The objective of this program is the development of an extracorporeal pulsatile assist device (EPAD), a valve-less diastolic augmentation pump with variable stroke volumes up to 80 ml per beat. The EPAD is designed as a low cost, disposable device whose initial application will be as a temporary right ventricular assist device in conjunction with the use of a left ventricular assist device (LVAD) for patients in reversible biventricular failure. The EPAD also will be usable ultimately as a temporary left heart assist device which, compared to the intra-aortic balloon pump (IAPB), provides any desired stroke volume and delivers its output into the ascending aorta for maximal effectiveness. The EPAD design permits rapid open-chest cannulation of either the pulmonary artery or aorta without the need for an end-to-side anastomosis of a vascular graft for blood access. Because the device is readily manufacturable and uses simple molded components, it is likely to be cost-competitive with the IAPB when produced in quantity. Phase I development will consist of prototype fabrication and in vitro characterization, followed by a series of acute in vivo studies using the EPAD as a right heart assist device with a model of induced right ventricular failure.